1. FIELD OF THE INVENTION
The invention refers to a device for detecting neps or the like in a carded textile fiber fleece band.
Carded fiber fleece bands produced by carding machines inevitably contain a certain number of so-called neps and/or impurities. Neps are knots or accumulations of fibers of different sizes. The reasons are various for such neps in carded fiber fleece bands. They may be found in the characteristics of the raw material, in the operation of the breaker card or in the clothing of the carding cylinder. The control of the frequency of neps and impurities present in the fiber fleece therefore can be used as an indication for the proper operation of the carding machine and for the elimination of possible defects. Especially, the wear of the clothing of the carding cylinder and the proper time for resharpening or exchanging the clothing can be determined.
2. DESCRIPTION OF THE PRIOR ART
For determining the number of neps, it was common practice to remove a piece of the fiber fleece from the band from time to time in order to analyze this sample. For the analysis the band is stretched by means of a stretching device and illuminated from below. From the upper side the fleece is examined visually through a magnifying lens. The neps thereby can be visually detected and counted as dark points on the bright background of the translucent stretched fleece. This known method, however, has the disadvantage, that a sample of the fiber fleece has to be removed from the band for the mentioned analysis. Therefore, this analysis cannot be made continuously, but only in relatively long intervals and with a need for additional personnel. In the examination of the sample a certain estimation of the respective person is inevitable, so that the result of the analysis is not generally valid, but depends on the respective person.